1 Field of the Invention
The invention relates to treatment of aldehydes for the purpose of complying with waste disposal requirements established by federal and state environmental protection agencies.
2 Description of Related Art
Waste disposal of aldehydes has become increasingly more difficult over the years. Law requires treatment of wastes containing a certain amount of aldehyde prior to placement of the waste into the environment. The extent of such treatment may vary depending upon the location of where the waste is generated and the stringency of the environmental standards in that area. For example, waste containing aldehyde may be classified as a hazardous waste in California under 22 CAL. CODE REGS., TIT. 22, xc2xa7 66696. Formaldehyde also may be considered a hazardous waste on the federal level under 40 C.F.R. xc2xa7 261.33(e) if it is a commercial chemical product (e.g., pure technical grade formaldehyde or formaldehyde is the sole active ingredient of the product that is to be disposed). Every state has an environmental regulation that is at least as stringent as this formaldehyde standard. State regulations also may be more stringent than this standard.
Additionally, facilities that discharge waste water to Publicly Owned Treatment Works (xe2x80x9cPOTWxe2x80x9d) or directly into navigable waters may be required to meet standards that are established by a government agency. The standard may vary for each facility depending upon the quality of the receiving water and the concentration of aldehyde found in the waste water that is discharged into the environment by industry in that area.
Waste containing aldehyde may be generated by a variety of processes. For example, aldehydes such as glutaraldehyde and ortho-phthalaldehyde (xe2x80x9cOPAxe2x80x9d) are used in disinfecting medical devices or instruments. Waste containing aldehydes also may be generated by painting operations, stripping operations related to floors, or other manufacturing operations.
Typically, ammonia and sodium bisulfite (xe2x80x9cSBSxe2x80x9d) are used to treat many aldehydes. These compounds, however, have not proven to be effective at neutralizing OPA in accordance with environmental regulations.
A waste is classified as a hazardous waste in California if the waste being examined xe2x80x9chas an acute aquatic 96-hour LC50 less than 500 milligrams per liter (mg/L) when measured in soft water (total hardness 40 to 48 milligrams per liter of calcium carbonate) with fathead minnows . . . xe2x80x9d 22 CAL. CODE REGS., TIT. 22, xc2xa7 66696. LC50 represents the concentration of a waste that is necessary to kill 50% of a particular animal exposed to a waste.
Note that a nonhazardous waste is generally considered by federal and state environmental agencies as a waste that does not satisfy the criteria set forth in defining a hazardous waste. Therefore, wastes generated in California that have a LC50 greater than 500 mg/L are nonhazardous wastes and wastes having LC50 less than 500 mg/L are classified as hazardous. SBS, for example, in combination with OPA, produces a product that is generally considered hazardous under California environmental law as shown in Table 1 by LC50 being consistently below 500 mg/L. For this study, CIDEX(copyright)OPA (commercially available from Advanced Sterilization Products(copyright), a Johnson and Johnson Company of Irvine, Calif.) was used to supply the OPA.
In addition to lacking the ability to effectively neutralize OPA, ammonia and SBS are problematic since they may be harmful to the environment.
FIG. 1 shows that when OPA is combined with SBS at the molar ratio of SBS/OPA=4:0 for 30 minutes, OPA has been neutralized since the OPA concentration is nondetectable in a high performance liquid chromatography (HPLC) analysis method, which has detection limit for OPA at 10 ppm. However, the end product is still classified as a hazardous waste as shown in Table 1. Therefore, even though the aldehyde is neutralized completely by a neutralizer, the end product may still be a hazardous waste.
Although glycine has been shown to neutralize glutaraldehyde (see H. Y. Cheung and M. R. W. Brown, Evaluation of Glycine As An Inactivator of Glutaraldehyde, 34 J. PHARM. 211 (1982)), the toxicity of reaction products of glycine has not been studied. Therefore, it is not known from this article whether the reaction product is nonhazardous. Accordingly, it is desirable to have a neutralizer that effectively neutralizes aldehydes in compliance with environmental standards and is less toxic to the environment.
There are a number of other challenges associated with treatment of aldehydes. One is to find a resulting end product that does not introduce any additional problems over the initial neutralization proposed. For example, it has been reported that treatment of aldehydes with neutralizing amino acids forms Schiff""s bases which may have the effect of reverting back to the untreated aldehydes under certain conditions.
A method of solving the reversion problem is disclosed in commonly assigned and co-filed patent application U.S. Ser. No. 09/747,230, (Attorney Docket Number ASP-009), filed Dec. 22, 2000. The present invention offers another solution to treating aldehydes in a manner that does not require additional treating agents.
A device and method for removing aldehydes from a stream is disclosed. In one aspect, the invention provides a generally nonhazardous means for removing aldehydes in accordance with applicable environmental regulations prior to disposal.
In one embodiment, a method and device are disclosed for removing aldehydes from a waste stream comprising the step of:
a) contacting the waste stream containing the aldehyde with a solid primary amine thereby binding the aldehyde to the solid primary amine.
In other embodiments, the methods and devices include the solid primary amine comprising a compound having primary amine functionality which is chemically bonded to a support, preferably silica.
Advantages of this invention include treatment of aldehyde-containing wastes which will minimize or eliminate discharge of aldehydes and their derivatives to the environment. Also, since the treated waste is immediately disposed after treatment, there is no risk of mistakenly re-using of the treated waste. The invention also avoids the need to add chemicals to neutralize the aldehyde. In preferred embodiments, when support materials are used that involve use of high surface area particles, such as silica, any bio-hazard materials left in the used disinfectant solution are captured. Also, when silica is used, it affords an inexpensive source for support particles and amination of silica is a simple process. Once the invention treatment device has reached its capacity, it may be simply disposed according to solid waste disposal guidelines.
Additional features, embodiments, and benefits will be evident in view of the figures and detailed description presented below.